Tim is basically permanently out of soundboards too. MR has stopped selling out returns. That's the story as I've heard it... it's the reason people are srambling to find a solution.

I don't think batteries and sound is going to happen in the ribbed section. In my Qui-gon-ish one I gave up on the AA's and I had a lot more room.

Corbin's will have to be in the center so the batteries either have to get smaller or split up. If you're set on AA's then you could split it at 2 below and 2 up in the ribbed section. Since it is rechargables I'd go for 4AAA's.